1. Field of the Invention
The present invention relates to an infrared ray detector, and more particularly, an infrared ray detector including intermitting means for intermitting an incident infrared ray. An infrared ray detector for detecting existence, temperature and the like of substance by the infrared ray radiated by the substance have been widely put into practice. However, for example, in an infrared ray detector such as a pyroelectric type infrared ray detector for generating electric charges responsive to change of an amount of an incident infrared ray, it is necessary to intermit periodically an incident infrared ray in order to ensure a precise measurement. The present invention relates to an infrared ray detector including such means for intermitting these infrared rays.
2. Description of the Prior Art
Conventionally, as means for intermitting infrared rays incident upon an infrared ray detector, an apparatus such as shown in FIGS. 1A and 1B has been used. The apparatus is disposed in front of an infrared ray detector 1 and comprises a motor 2 and a metal plate chopper 3 rotatably driven in a periodical manner by the motor 2. However, the apparatus as shown in FIGS. 1A and 1B requires a relatively large chopper 3 which prevent the apparatus from being small-sized. Furthermore, since the motor 2 sometimes irregularly rotates, the chopper 3 cannot be precisely and periodically rotated and thus there was a drawback that the precision for detection is relatively low.
In order to solve the above described problems, a structure for intermitting an incident infrared ray using a shutter body connected to a piezoelectric vibrator is disclosed in the Japanese Patent laying open Nos. 54418/1980 and 54419/1980 which are laid open for public inspection on Apr. 21, 1980, respectively. However, since the whole shutter body moves across the path of the infrared ray, the amount of movement of the shutter body must be made large and thus it is necessary to use a relatively large piezoelectric vibrator. As a result, it can be hardly said that such structure contributes to a miniaturization of an infrared ray detector.
On the other hand, the present inventors disclosed in the Japanese laying open No. 160628/1981 laid open for public inspection on Dec. 10, 1981, the structure in which a pair of opposing portions vibrated by a piezoelectric vibrator, which comprises infrared ray transmitting portions and infrared ray non-transmitting portions, are disposed in front of a window for incidence of an infrared ray in an infrared ray detector. However, in this prior art, besides an infrared ray detector, it is necessary to include an additional structure having a piezoelectric vibrator and the like and thus just as each prior art as described in the foregoing, it does not contribute to a miniaturization of an infrared ray detector per se.